Leaflet/ISSUE_TEMPLATE.md

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## How to reproduce

- Leaflet version I'm using:
- Browser (with version) I'm using:
- OS/Platform (with version) I'm using:
- step 1
- step 2

## What behaviour I'm expecting and which behaviour I'm seeing

## Minimal example reproducing the issue

- [ ] this example is as simple as possible
- [ ] this example does not rely on any third party code

Using http://playground-leaflet.rhcloud.com/ or any other jsfiddle-like site.